This invention relates to a method and apparatus for dispensing predetermined amounts of liquid by weight into a container and, in particular, is directed toward an improved apparatus and method for dispensing liquid into a container of the type shown in commonly-assigned U.S. Pat. Nos. 4,211,263, 4,337,802 and 4,494,583, said patents are hereby incorporated by reference.
Depending upon the nature of the liquid, any of several filling techniques may be utilized to dispense a predetermined metered amount of liquid into the container. If the liquid is susceptible to foaming, it is typically the practice to insert a filling lance (the conduit through which the liquid passes into the container) into the container such that the lower discharge end of the lance is in close proximity to the bottom of the container.
In the method described in the patents incorporated by reference, the movement of the filling lance, sometimes referred to as a conduit, is normally initiated by the operator of the filling apparatus. A predetermined small amount of liquid is then slowly introduced into the container until the level of liquid in the container rises above the discharge end of the lance. Since the discharge of the lance is thereafter below the level of liquid in the container, most of the remaining weight of the liquid may be introduced into the container at a relatively faster fill rate until the fill rate is slowed down (to a dribble fill rate) just before the final weight of liquid has been dispensed.
During the fast fill operation, the lance is not raised within the container until a predetermined volume of fluid is added to the container. The lance is then raised to a position at which it finishes filling the container at a dribble fill rate. After the dribble fill is completed, the lance is fully withdrawn.
A significant problem commonly encountered by container filling apparatus such as that described in the incorporated patents was that the filling lance of the drum filling apparatus was immersed in the fill fluid during the filling operation. This is disadvantageous for certain materials such as quick setting polymeric films and the like. Even the wiper ring, disclosed in incorporated reference, U.S. Pat. No. 4,211,263, which is used to remove excess material, is often ineffective in keeping the filling lance clean when the drums are being filled with these types of film forming materials.
This invention provides an apparatus and a method for inhibiting the build-up of liquid materials on the filling lance of a drum filling apparatus.
One advantage of the present invention is that it reduces the quantity of liquid that may spill outside of the drum or container.
Another advantage of the present invention is that it reduces the quantity of noxious or toxic fumes that certain liquids may emit.
Still another advantage is that the operation of the drum filling apparatus will not be adversely affected by the buildup of fluids on the filling lance.